Automatic device for automatic firearms



1933 3 Sheets-Sheet 1 IN] 'ENTOR. SABURO WATANABE 8Y2 :22 2g A'TTORXEYS.

Feb. 2, 1937. s. WATANABE AUTOMATIC DEVICE FOR AUTOMATIC FIREARMS Filed Dec. 19,

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Feb. 2, 1937. s. WATANABE AUTOMATIC DEVICE FOR AUTOMATIC FIREARMS Filed Dec. 19, 1933 3 Sheets-Sheet 2 6A BURO WAT/S IQ XE'F';

%%gfi Feb. 2, 1937. s. WATANABE 2,059,432

AUTOMATIC DEVICE FOR AUTOMATIC FIREARMS 3 Sheets-Sheet 3 Filed Dec. 19, 1933 V Fi 5.

INVENTOR.

SABURO WATANABE 22 Q; A TTORNEYS.

Patented Feb. 2, 1937 UNITED STATES PATENT OFFICE Saburo Watanabe, Kita-Shinagawa, Shinagawaku, Tokyo, Japan Application December 19, 1933, Serial No. 703,044

' In Japan December 30, 1932 3 Claims.

This invention relates to an automatic firearm having a crank and a toggle and accordingly having three pivoting pins, an automatic device in which the location of the central pivoting pin above a line connecting the other two pins in the direction in which bending occurs is avoided and this pin instead located either below said line in the-opposite direction, or on the same line with said pins in order to resist the initial blow-back pressure acting on the breech block, the positive deviation being given thereto by pressure of. the gas coming out of a gas port provided near the muzzle, while the breech block is subsequently opened by the blow-back vide an automatic device for automatic firearms which is simple in construction while steady in operation.

In the accompanying drawings forming part hereof, Fig. 1 is a longitudinal section of the automatic device embodying the invention and showing the parts when the breech is closed.

Fig. 2 is a longitudinal section of the same showing the parts when the breech is opened.

Fig. 3 shows a longitudinal section of the main parts of the device when they are closed.

Fig. 4 shows the same section as Fig. 3 when the parts are atinitial opening position.

Fig. 5 shows thesame section as Fig. 3 when the parts are fully opened.

Fig. 6 showsa perspective view of the detailed parts of. the device.

Figs. 7, 8, 9, 10, -11 and 12 show respectively a transverse section along the lines AB, CD, EF GH, IJ and KL, of Fig. l.

The receiver is composed of an upper half 2 and a lower half 3 and the barrel is screwed into the front end of the upper half 2 of thereceiver. This half 2 is provided with a longitudi- 40 nal groove with which the breech block 4 is slidably engaged. At the rear part of the receiver, there is provided a crank pin 36 which serves as a pivot for a crank 6. The front end of the crank 6 is bifurcated to embrace the rear end of a toggle or connecting rod 5, both being connected by means of a toggle pin 34. The front end of the toggle i is also bifurcated to envelop up to about middle part of the breech block 4, the two pairs being connected by means of a breech block pin" is an actuator of open frame form extending from the lower side of the crank to the same side of the chamber about the magazine 31. Into the front end of. the actuator a piston rod 64 is screwed and a piston 65 is fixed to the front pressure. The object of the invention is to proend of the piston rod 64 by means of a nut or head 66,.the piston 65 is inserted into a gas chamber Hi from the front. The gas port of this chamber I9 is preferably provided at the most ad'- vanced position within the limit which will not 5 hinder bayoneting. The rear end of the actuator is guided by the lower half 3 of the receiver to contact with the end of the crank 6 and is normally pressed backward by means of. a return spring 50 arranged at the front thereof. The return spring 50 is guided in its front part by a return spring guide SI and presses the guide against the rear face of projecting rims 13 of the lower half of the receiver. The rims 13 run longitudinally, two in number, and between the 15 same a hammer I1 is pivoted by means of a hammer pin 20. A sear 4| and a trigger I are respectively pivoted to the lower half of the receiver by means of a sear pin 42 and a trigger pin l6 and are connected to the hammer l1 through a hammer spring spindle 22 which is pivoted to the hammer by means of a pin IS. The hammer spring spindle 22 forms a guide for a hammer spring 2|, passes through a hole of the sear 4|, thereby tends to impart a clockwise rotation to 25 the hammer I1 and that of a counterclockwise rotation to the sear 4|, so that when the hammer I1 is pressed down during rearward movement of the breech block 4; the end of the sear 4| engages with the notch provided at the lower side of the hammer l1. and thus stops the rotation of the hammer. When the trigger is pulled, a sear operating link I2 pivotally connected thereto pushes the rear end of the sear 4| so that the front end of the sear is lowered and thereby the hammer I1 is freed to rotate clockwise.

The breech block is provided in its longitudinal bore with a firing pin 3| which is loosely connected to the breech block by means of a firing pin stop 30. This pin is normally pressed rearward by means of a firing pin spring 32 and when struck by the hammer II, it fires the cartrid e.

In this invention, the line passing through the centers of the crank pin 36, the toggle pin 34 and the breech block pin 34 is not curved upward so that the gas pressure acting upon the breech .block does not produce any tendency of bending the parts [Fahd '6 so that the breech block is meanwhile kept in its .closed position. When 5 gas pressure is supplied to the gas chamber I0 through gas port l0 from the bore of the barrel I, the piston 65 is moved forward so that the piston rod 66 and the actuator are forced forward to compress the return spring 50. At the same time,

the rear end of the actuator I departs from the rotatable in counterclockwise direction. Further at the same time, an inclined portion surface Ia at the rear upper part of the actuator 1 pushes up an inclined portion 6a of the lower part of the crank 6 and thereby the initial motion for upward bending is imparted to the toggle and the crank links, and thereafter the parts occupy 'the positions as shown in Fig.2 due to the action of the blow-back pressure. That is, the rear end of the crank supports the rear end of the actuator I and a step do at the lower side of the breech block 4 engages with the upper edge of the return spring guide 5| during the rearward movement of the breech block, so that the return spring 50 is compressed from the front.

Thus, when the rear end of a cushion 52 preferably, made of leather and applied to the return spring guide, contacts with the rear wall of the actuator, the rearward movement of the breech block ceases and at once the return movement begins in which the return spring pushes the end of the crank through the rear wall of the actuator. Therefore the crank begins to rotate clockwise and the breech block is moved forward. In this instance, when a cartridge or cartridges is or are stored in the magazine 31, one of the cartridges is charged into the chamber. When the magazine 31 is empty, a lifting plate 39 comes to the uppermost position of the magazine 31 by means of a magazine spring 40 and thereby the forward movement of the breech block is limited, thus indicating that the magazine is empty. When the trigger is freed in this condition, two breech block stops 43, each of which is pivoted at each side of the front bifurcated parts of the trigger, and which is pressed from downward by means of a trigger spring 23 as shown in Fig. 1, are raised upward as the trigger rotates counterclockwise and the end of the stops engages with notches, not shown, provided in the rims, not shown, at both sides of the breech block, the rims being engaged with the corresponding longitudinal slots, not shown, at both sides of the receiver. By this engagement of the stops with t e notches of the rims, the breech block "is kept a its retired position. When the trigger is again actuated, the stops are disengaged from the said notches so that the breech block moves forward.

The breech block 4 is provided at its upper side with a T shaped slot in which a charger guide 24 is slidably arranged. This charger guide 24 is normally pushed forward by means of a spring 29 of comparatively small strength and its range of the movement is limited by an extractor pin 26. In the closed position of the breech block, the charger guide 24 is in the rearmost position as shown in Fig. 1, while in the opened position of the breech block, the guide projects from the forward end of the breech block as shown in Fig. 2 and forms a guide for the charger. An extractor 25 is pivoted on the upper side of the breech block by means of an extractor pin 26 and engages with the flange of the cartridge by the action of an extractor spring 28. An ejector 33 is loosely arranged within a longitudinal hole at the lower/side of the breech block and kept slidably in position by a pin. When .the breech block retires, the ejector 33 is struck by the forward end of the return spring guide 5! so that its fore end projects from the foreend of the breech block and ejects the empty cartridge case.

A pin tor the receiver has a section as shown in Fig. 1. when this pin is rotated 01006 by hand, for example, up to 90, the actuator is slightly moved forward so that the lower surface of the actuator is superposed upon the sear operating link I! and thereby the link I2 is prevented from being raised and the trigger is safely fixed. In this case, a part of the pin 8 contacts with the rear end of the crank so that the crank is prevented from being rotated.

When it is desired to open the breech by hand, the pin 8 is rotated counterclockwise from the position shown in Fig. 1 up to 90 and thereby the actuator I is slightly moved forward to free the rear end of the crank. Then the forward portion on both sides of the crank is gripped by fingers and pulled upward to bring it in a position shown in Fi 2.

The sight 65 is inserted in a T-shaped slot at the rear end of the receiver and is raised or lowered by means of a rack and pinion device, and is provided with the hole-sight at the top thereof.

The bottom of the magazine is covered by a floor plate 38.

The automatic device according to this inventionhas many advantages, such as the following:

1. The actuator is caused to run forward by the piston being blown forward and thus the piston rod is subjected to tension. Therefore the diameter of the piston rod may be made smaller than that of known gas operated types. Also there is no necessity of providing a guide for the piston rod. These facts make it possible to decrease the weight of the parts;

2. As the piston is blown forward, it is feasible to make use of a gas chamber of a very small volume and weight, and after forward movement through a small distance on the part of the piston, the gas is at once exhausted into the atmosphere, so that over-heating of the gas chamber is avoided while its cleaning is easy;

3. The return spring is first of all compressed by the forwardstroke of the piston so that no return force acts against the backward movement of the breech block, toggle and crank link. This fact enables the constructor to let a very small residual gas pressure act upon the front face of the breech block to positively actuate the link with suflicient steadiness;

4. When sticking occurs,a phenomenon of extraction of empty cartridges becoming difficult by close contact of the cartridge case with the wall of the chamber due to expansion of the case-the operation becomes unsteady in any known automatic firearm of blow-back type. In the new firearm, as the middle part of the toggle link is positively pushed outward, the empty cartridge is extracted by a strong force and thereafter the parts are sufficiently operated by the inertia;

5. As the rear end of the actuator engages the rear lower portion of the crank, the crank never rotates but that the actuator doesnot also run forward. Accordingly there is no danger even in cases of two step burning of powder due to accident or of an overcharge.

6. 'When the breech block is closed by operating the toggle joint, it is a very difficult matter to completely close it owing to re-bounding of the link due to resilient restoration and this has been indeed the dreadful drawback experienced by those skilled in the art. In the present new firearm, as the rear end of the actuator tightly engages the rear lower portion of the crank, the rebound of the mentioned objectionable kind at the closing of the breech block is entirely avoided;

by pulling the trigger only when the eccentricity of the toggle link is zero or minus and thus first moves the sear to operate the hammer;

8, The gas port may be provided at the foremost. practicable position which will not hinder bayonetlng so that the gas pressure acting in the gas chamber may be appreciably decreased.

Therefore the erosion in the neighborhood of the gas port is comparatively small and all the mechanisms are subjected tono abnormal forces, while no increase of the weight occurs owing to the fact that the piston rod, when operating, is subjected to tension, and not compression, although the position of the gas port is selected to be in such an advanced part of the firearm;

9. Contrary to most of the known automatic firearms, the return spring does not act to obviate the preopening of the breech block by its own resisting force, so that a very small and weak spring can be employed. Therefore, when the crank is raised by hand, the operating handle, if used, may be of very small size and even may be entirely omitted as exemplified in the drawings sothat it is easily raised by simply gripping the forward end of the crank so as thus to dispense with any projections therefore;

10. As the gas port may be provided in the foremost position, a very large part of the gas energy can be given to bullet;

11. As the beginning of the movement of the mechanism occurs after the bullet has departed from'the muzzle due to the foremost advanced positioning of the gas port, the percentage of failures of the bullet to hit due to vibration is greatly reduced.

Having now fully described my invention, I claim:---

1. In an automatic firearm having a bored barrel, a frame, a pin in said frame and a crank pivoted to said frame by said pin and having a free 'end, a breech block adapted to travel in line with and toward,the rear end of said barrel and having-a pin, a; link interposed between said breech block and crank and connected to the breech block by said second pin, a third pin connecting said crank to said link, said crank, link.

and breech block forming a toggle crank link mechanism having three pins and capable of breaking outwardly, means onqsaid crank preventing reverse or inward bending of said mechanism, said third pin being disposed in an intermediate position with respect to the other two pins having at least a zero deviation to the outward direction with respect to a line connecting said other two pins into which the mechanism bends, an actuator movable in general parallelism with the axis of the barrel adjacent to a portion thereof and in a normal rearward initial position abutting with its rear end the free end of said crank, a return spring retaining said actuator in its normal initial position, a gas chamber forming a piston cylinder parallel with the bore of said barrel and communicating directly therewith through a gas port located adjacent to the muzzle of the barrel, a piston reclprocably disposed in said cylinder forwardly of said gas port and capable of being projected in a forward direction therein by gas pressure entering said cylinder rearwardly of said piston from said barrel, a piston rod upon the piston operatively connected to said actuator so .as to cause the latter to move with said piston, a projection upon the crank extending in -a direction opposite to the direction of bending of the mechanism, and a corresponding projection upon the actuator engaging against and positively displacing said crank outwardly, so as to effect initial positive deviation of the toggle crank link mechanism from normallocked position upon forward movement of the actuator by the piston and allow subsequent rearward movement of said mechanism by breech block pressure.

2. An automatic device for an automatic firearm according to claim 1, wherein the projection 'upon the pivoted crank is formed with a lower,

upper, forwardly inclined surface portion which,

during the forward movement of said actuator makes contact with said lower, rearwardly inclined surface portion of the projection on the crank and raises the latter and initially breaks the toggle crank link mechanism positively outward.

3. An automatic -device for an automatic firearm according to claim 1 wherein the frame has an upwardly open and longitudinally elongated slotted portion partly occupied by the toggle crank link mechanism and within which the crank is pivoted and the breech block is longitudinally movable, and in which the crank, toggle link and breech block'members in normal initial position are substantially aligned and have their upper ,surface portions-aligned and forming a portion of, and conforming generally withpthe upper outline of the firearm.

SABURO WATANABE. 

